Electronic voltmeter with a plurality of inputs



March 4, 1952 P. w. cRAPucHETTEs 2,588,209

ELECTRONIC VOLTMETER WITH A PLURALITY oF INPUTS Filed Dec. s, 1947 /IVPUT yOU/755 J' 001962" J H15 ATTORN EYS Patented Mar. 4, 195,2v

UNITED sfrA'rEs atrasos PATENT ol-FICE N ELECTRONIC VOLTHETEB WITH A PLURALITY F INPUTS raul w. onpucnen'es, rs1 au, cau'f.,lauicnnr to Michael R. Klein, NSan Francisco, Calif.

Application December s, im, sel-a1 No.4 '190,281

(ci. r11-95)` 2 Claims.

` vide an electronic device for combining or mixing a number of independent voltages to give an output current, the magnitude of which depends upon the phase, sense, and magnitude of some or l 2 Control grids l, 1, l, 8 are fed from potential dividers Il, Il, i2, I3. respectively.V The upper terminal of each of said dividers is connected to vits respective input voltage source. while the lower terminals are connected in common to the negative terminal I of the space current source. as

.well as to the cathode Il of 4the discharge device through a grid bias voltage supply source con- -n'ectable across terminals Il, il.

Another embodiment of the present invention is shown in Figure 2. Here again there is provided an electron discharge device l1, this onereother timerlags, and capable of extreme speed oi the various voltages fed to the device, and with relatively little power being drawn therefrom.

Other objectsV and advantages of the device herein described and claimed will appear from the speciiication and claims appended thereto taken in conjunction with the accompanying drawing wherein:

Figures l, 2 and 3 are circuit diagrams depicting different embodiments of my invention.

In the most general method of carrying out the invention, there is provided an electron discharge device with associated power` supply, the space current of which is controlled by relatively inde:- pendent means responsive to a number of independent voltages, the magnitude of the space current providing the desired indication oi' the combined value.

One method of accomplishing this end is to apply, through appropriate potential dividers, each input voltage to separate control grid in a multigrid electronic discharge device. If all grids are so positioned as to have suitable transconductanceA characteristics with respect to the common space current, this method is capable of fulfilling the objects of the invention as set forth above.

Such a circuit arrangement is shown diagrammatically in Figure l, whereina hexode electron discharge device I is provided with space current from a' direct current power source (not shown) through terminals 2 and 3, the space current being indicated by a device 4 such as a meter or signal device connected between positive terminal 2 and the anode i of the electron discharge device.

quiring a minimum of only three electrodes including an anode Il. a control grid I9, and a catho de 20. Like in the preceding embodiment, I also include space current power supply terminals 2| 22, an indicator 2l, and grid bias voltage supply terminals 24, 2l

A resistor 26 is connected across the input to the device |11 and is itself common to all voltage dividers applying input voltage to grid I9. The separate sections oi these voltage dividers are numbered 2l, 28, 29, 30.

If the resistance of sections 2140 inclusive of the dividers be large in comparison with the resistance of common section 26,V there will :be little interaction between the various input voltages.

What little interaction there is, may be reduced still further if necessary by connecting a capacitor 3| across resistor 26. This has the effect of reducing the slope of any steep waveironts of pulses of voltage from any of the 'input sources,

so whatever interaction there may be between such sources will be less likely to cause erroneous indications in the anode circuit oi the electron discharge device.

A third variant of the basic conception is indicated schematically in Figure 3. Here the operation is identical with the circuit arrangement of Figure 2, and corresponding circuit elements bear corresponding reference numerals in each ngure.

The arrangement of Figure 3 differs from that of Figure 2 in that the input voltage on control grid I! of the electron discharge device I1 is infiuenced by an additional increment derived from the space current of a second electron discharge device I2, the anode of which is directly connected to grid i! of the device I1, while the cathode 35 is connected through an appropriate bias source as represented by terminals 3B, 31 to the other side of the input'circuit feeding the device I1.

The control grid 3l of the device 82 is excited s6 by some ot the same input voltages by way oi accesos 4 vadirectvoltagegiidbiassourceintheravtbode 3 involving separate redstors It,

all. etc. and a common resistor I! across the input electrodes of the discharge device, as are applied to control grid I9 of the device Il, with the result thatphase reversal oi'v input voltage in the device 82 tend to reduce the response of the device I1 to those components of overall input voltage applied to each grid simultaneously.

Like with the resistor 28, a capacitor should preferably be connected across' the corresponding resistor Il.' v

By appropriate adjustment of the ratio of the potential dividers concerned, and by proper selection of the bias voltages applied to lthe cathode circuits of each device, it is possible exactly to cancel any desired input voltage component, or alternatively to reverse the sense of predetermined components if desired.

The above described circuits have many useful applications in the art. One in particular, for

which it is well adapted, is in the conversion of the relatively unintelligible indications of an electronic decade counter such as disclosed in the application of Michael R. -Klein, Serial No. 634,031, illed December 10, 1945, now Patent No. 2,557,385, issued June 19, 1951, and which is based on a trigger circuit illustrated and described on pages 353-356 ot 'Iheory and Application of Electronic Tubes, second edition by Herbert J. Reich. In such application. eachof the variousv dividers oi the mixing circuit oi' the present'invention will derive its voltage pulses from one of the output circuits of such electronic counter, and in response to the mixing of such pulses as previously vpointed out, the indicator in the output of the mixing circuit, may be made to register a legible equivalent oi' the value which the electronic counter may be registering at any instant.

While I have disclosed certain specic embodi-A ments of my invention in detail, the same is subject to alteration and modiilcation without departing from the underlying principles involved, and I accordingly, do not desire to be limited in my protection to the specific details illustratedv and described except as may be necessitated by the appended claims.

Iclaim: A 1. An electronic mixer adapted for providing an indicating current responsive to a plurality of input voltages, comprising a rst and second electron discharge device each including an anode,

circuit of said nrst device, and a plurality of potential dividers including a common resistive e1e ment shunted by a capacitor and the space current path of said second device, said potential dividers being connected between said grid bias source and control grid of said nrst device, and

having purely resistive portions thereof terminating one in each source of said mst-mentioned input vo es, said second device having control gridpo `tial derived similarly from at least one potential divider connected to at least one of said sources o! mst-mentioned voltages.

2. An electronic mixer adapted for providing an indicating current responsive to a` plurality o! input voltages, comprising at least a ilrst and second electron discharge device each including an anode, cathode, and control' arid. direct voltage cathode, and control grid, .direct voltage power supply providing space current for said rst electron discharge device, current indicating means responsive to space current of said rst device,

power supply `providing space current for said first device, current indicating means responsive to space current of said ilrst device, a direct voltage grid bias source in the cathode circuit of said ilrst device, and a plurality of potential dividers including a common -resistive element shunted by a capacitor and by the space current path o! said second device, said potential dividers being connected between said grid bias source and control grid of said ilrst device and having purely resistive portions thereof terminating one in each source of said first -mentioned input voltages. said second device having control gridpotential derived similarly from at least one potential divider connected to at least one of said sources vofiirst-mentioned voltages, a separate grid bias source for said second device in the cathode circuit thereof, adjusted in magnitude to neutralize certain undesired components of space current in said ilrst device when such undesired component's are impressed simultaneously through separate potential dividers upon control grids of both said devices.

` PAUL W. CRAPUCHE'IIES.

REFERENCES CITED The following references are of le of this patent:

UNITED STATES PATENTS record in the 

